Welcome to the Triatomic Hydrogen Group at the Department of Molecular and Optical Physics - University of Freiburg, Germany
Novel Photofragment Spectrometer for the Investigation of Molecular Three-Body Decay
M. Braun, M. Beckert and U. Müller
Department of Molecular and Optical Physics, Albert-Ludwigs-Universität, Hermann-Herder-Strasse 3, D-79104 Freiburg, Germany
We have developed a novel photofragment spectrometer to investigate the fragmentation
of neutral molecules into two, three, and more neutral fragments. The parent molecules are laser
prepared in a fast beam. The photofragments are detected in coincidence by a time- and
position-sensitive detector which consists of multichannel plates and delay line anodes.
We have developed new electronic pulse routers which allow us to measure consecutive fragment
hits with dead times as low as a few nanoseconds. A new algorithm has been developed
to determine for each triple hit the momentum vectors of the three fragments from the measured
arrival time differences and positions. To demonstrate the performance of the spectrometer,
we have investigated two- and three-body decay processes of laser-prepared triatomic
hydrogen molecules H3 into H + H2 fragment pairs as well as into three
hydrogen atoms H(1s) + H(1s) + H(1s). For two-body decay of vibrationless
(N = 1, K = 0), we have found that the resolution in the kinetic energy
release spectra is far better than that achieved in previous investigations.
With the new spectrometer, kinematically complete investigations of the breakup of a neutral
molecule into three neutral fragments have been performed. The final state distributions in the
three body decay of laser-prepared H3 molecules show pronounced structures which give
insight into the complex molecular decay mechanisms. ©2000 American Institute of Physics.
©2000 Rev. Sci. Instruments, 71,4535 (2000)
39.10.+j, 39.30.+w, 33.80.Gj, 07.77.Gx, 84.30.Sk, 07.05.Hd